West Ham United winger Manor Solomon was called a "baby killer" by pro-Palestine activists because of his service with the Israel Defence Forces.
Activists, described as thugs, called for the club to "kick out" the Israeli player in a campaign supported by local councillors.
Masked and hooded protesters filmed a video outside London Stadium, the club's home in east London, threatening the winger.
In a robotic-sounding voice one participant said: "We do not agree with the signing of Manor Solomon. We'll continue to raise our voices until he is out of the club."
The incident follows chants from some West Ham fans of "Manor Solomon's on my mind/And he hates Palestine" during the August 16 match at Burnley.
Solomon, 27, had joined West Ham only days before the club asked supporters to stop the chanting.
The Tower Hamlets Palestine Solidarity Network, created and run by councillor Faysal Ahmed, amplified the abuse.
Sharing a screenshot from the video, the group wrote: "Activists hammer home the message: Kick out baby killer Manor Solomon from West Ham United."
At least seven other Tower Hamlets councillors are listed as members of the group's Facebook page.
Solomon was conscripted for mandatory military service in the IDF in December 2017.
That enlistment occurred seven years before the Gaza attacks that followed Hamas's killing of at least 1,195 Israelis on October 7, 2023.
Alex Hearn of Labour Against Antisemitism said: "Solomon's done nothing except be an Israeli footballer. Hounding a player out of his job because of where he comes from is not activism, it's bigotry. No elected councillor should be anywhere near it."
